A Typical Cactus Flower

However much the cactus offends by the ugliness of its grim armor it more than makes up by the beauty of its flower. Most cactus flowers are large, delicate and of brilliant color; ranging from perfect whites to deep reds-from bright yellows to rich purples.

This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 1 Chapter 1